1. Field of the Invention
The present invention generally relates to document processing apparatuses for processing documents having a plurality of versions, and more particularly to a document processing apparatus that unifies management of document contents (content data) of each version to share the document contents in a case in which the same document contents exist between different versions, so that a storage area can be reduced.
2. Description of the Related Art
Recently, to manage documents and images that are newly created, edited, processed, or the like based on one document or one image, sharing contents of the document or the image has become more common. Regarding this, for example, Japanese Laid-Open Application No. 8-44718 discloses a method for sharing document components among different documents.
Alternatively, managing the contents of the documents or the images by different versions is a widely used procedure. In this version management, components having the same contents are shared among different versions. Therefore, it is possible to reduce the storage area required to store the contents, and to reduce the workload necessary for processing the document or the image.
However, there are problems as follows if only version management is conducted. For example, if only the content data, which are relatively a greater amount than bibliography data, are managed for each version, the storage area cannot be effectively utilized. Even if the contents of the document are not changed when the document is edited, the number of versions is increased after the document is edited. In this case, the contents of the document are stored as additional contents, in spite of being the same as before being edited. Accordingly, extra storage area is used.